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  1. #1

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    light meter for extreamly long night exposures?

    Hello

    I am looking for a light meter for extreamly long night exposures ( i have only found a few that can go to upto 30 min). and i dont want to be calculating manually as a I need accurate readings and that why i hope to find quite sensitive light meter for longs exposures please.

    Could you tell me which meter do you think you could recomend me please?

    Thank you

  2. #2
    Katie's Avatar
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    Would be interested to see what others say on this as I have always been curious about how to determine proper loooong exposures!

  3. #3
    hobbes's Avatar
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    Quote Originally Posted by chihiro View Post
    Hello

    I am looking for a light meter for extreamly long night exposures ( i have only found a few that can go to upto 30 min). and i dont want to be calculating manually as a I need accurate readings and that why i hope to find quite sensitive light meter for longs exposures please.

    Could you tell me which meter do you think you could recomend me please?

    Thank you
    For the sake of not making your works Schwarzschild effect impaired, sometimes you GOTTA be calculating manually, no matter how sophisticated lightmeter you will get; Especially for ~30 minutes exposures Take a look at that thread: http://www.apug.org/forums/forum48/9...ld-effect.html
    cheers
    Dominik
    http://distantmoon.pl

  4. #4
    Two23's Avatar
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    It won't do you much good to have a light meter that can measure even longer than 30 minutes, even if that were to exist. You're going to run smack into reciprocity failure with any film. It will still come down to some trial and error.


    Kent in SD

  5. #5
    brian d's Avatar
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    I agree with the others, you are probably going to have to calculate reciprocity failure or find a reciprocity chart for whatever film you are using.
    Now having said that I do have a old Gossen "cds Super Pilot" that goes up to 2 hours.
    Real men use Speed Graphics and flashbulbs.

  6. #6
    Lee L's Avatar
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    A label for 30 minutes on the dial doesn't mean a meter has the best low light measuring capacity. Look for specs that show the lowest EV to which the meter can accurately measure. The LunaPro series are among the best, especially the LunaPro SBC (US market model name, Profisix in others) which goes to about EV -4, and perhaps some later models that I'm not that familiar with. Other brands have a few models that go low, but Gossen seems to be ahead in that area across models. You should be able to find specifications.

    As others have said, by 30 minutes metered exposure time you're running into serious reciprocity failure with pretty much all films. Use Fuji Acros if you want to minimize that in B&W. No commercial meter I've seen is set up to calculate reciprocity failure, and that varies radically across films anyway. Your best bet is to read up on reciprocity failure and how to calculate it (plenty of that here on APUG), find a film to stick with, make notes based on your experience, and keep a printed table of adjustments, either by opening up aperture or lengthening exposure. Note that extending exposure time involves a compounding effect, just like compound interest.

    You can't make it as simple as you seem to want and still have the accuracy you desire. Mentioning the kind of film you want to use could probably bring recommendations for lowest reciprocity failure. B&W, color negative, color transparency? There is also the problem of color shift if you're using color, caused by different reciprocity characteristics in the different color layers.

    Lee

  7. #7
    holmburgers's Avatar
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    Quote Originally Posted by Lee L View Post
    A label for 30 minutes on the dial doesn't mean a meter has the best low light measuring capacity. Look for specs that show the lowest EV to which the meter can accurately measure. .... Note that extending exposure time involves a compounding effect, just like compound interest.... Lee
    Lee is right. The time means nothing really. I mean, if you are using ASA of .01 that might be a 30 minute exposure in bright sunlight...

    So like he says, you need to look for a meter with the lowest EV. The silicon-blue meter in my Canon EF (FD body) goes to EV -3 I believe, which is enough to accurately read a full-moon lit landscape.

    However Lee, I'm not sure what you mean exactly by extending time involves a compounding effect. If you are metering 30 minutes exposure, you of course need to apply reciprocity failure compensation, but this new & longer time requires no further compensation (compounding). Right?

  8. #8
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    acros and tmy2 are the only films I use for night work...

    not that I'm an expert or anything but I've done enough testing to use them
    for my meagre purposes

    I did a bit of exposure bracketing using acros and pretty low-light,
    http://www.flickr.com/photos/stormiticus/4769811341/

    I've done the same with tmy-2, came up with about 9 minutes for a full moonlight scene...

    I guess I'm saying you'll need your own tests, but then you'll 'own' those films,
    i.e. really know the film's capabilities from experience

  9. #9

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    the luna pro sbc is a great lowlight meter, and
    another great resource is a black cat exposure guide
    http://www.blackcatphotoproducts.com/guide.html

    i was given one years ago, and it works pretty well !
    john

  10. #10

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    Thanks for all your answer,

    can you recommend me then some useful articles or forum treats with tips about 'how to calculate & reciprical failure' ,please
    thank you

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